1. Field
The present inventive concept relates to a display device.
2. Description of the Related Art
A liquid crystal display device, which is one of currently widely useful display devices, operates in a manner such that voltage is applied to electrodes (a pixel electrode and a common electrode) formed on two substrates facing each other to control the alignment of liquid crystal molecules in a liquid crystal layer interposed between the two substrates, thereby adjusting the amount of transmitted light.
Such a liquid crystal display device includes a thin film transistor connected to the pixel electrodes. The thin film transistor is utilized as a switching element for independently driving individual pixels in the liquid crystal display device.
Specifically, the thin film transistor is a switching element for controlling data signals transmitted to the pixel electrode through data lines in response to gate signals transmitted through gate lines at individual pixels, and includes a gate electrode connected to the gate lines, an active layer (a semiconductor layer) for forming a channel, a source electrode connected to the data lines, and a drain electrode spaced apart from the source electrode with the active layer interposed therebetween in a plan view.
The thin film transistor may include, for example, a bottom gate type thin film transistor and a top gate type thin film transistor, depending on the position of the gate electrode with respect to the active layer. A bottom gate type thin film transistor is configured such that the gate electrode is located under the active layer, and a top gate type thin film transistor is configured such that the gate electrode is located on the active layer.
Furthermore, since the top gate type thin film transistor is configured such that the gate electrode is located on the active layer, light emitted from a backlight unit that is positioned under the substrate may have an influence on the active layer. Therefore, the liquid crystal display device including the top gate type thin film transistor may further include a light blocking layer for blocking the introduction of light into the active layer from the backlight unit.
However, the light blocking layer is disposed in floating state that is not electrically connected to a voltage source, and thus may cause parasitic capacitance with peripheral constituents, for example, the gate electrode, the source electrode or the drain electrode, due to static electricity. Such parasitic capacitance may deteriorate the characteristics of the thin film transistor as a switching element, undesirably degrading the operational reliability of a display device.